The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Internal combustion engines produce drive torque that is transferred to a drivetrain. The drive torque is transferred through a transmission that multiplies the drive torque by a gear ratio. Transmissions generally include multiple gear ratios through which the drive torque is transferred. Automatic transmissions automatically shift between gear ratios based on driver input and vehicle operating conditions. Traditionally, automatic transmissions include a forward clutch and a reverse clutch for actuation between forward and reverse driving conditions through the use of a pressurized hydraulic fluid. The hydraulic fluid is typically pressurized during operation of the engine.
Hybrid powertrains typically include an electric machine and an energy storage device (ESD) such as battery or super capacitor. In one mode, the electric machine drives the transmission using energy stored in the ESD. In another mode, the electric machine is driven by the engine to charge the ESD. When operated in the first mode, the hybrid vehicle may be operated without the use of the engine. When operated without the use of the engine, an auxiliary pressurizing mechanism, such as an electric pump, is typically used to pressurize the hydraulic transmission fluid to provide for engagement of the forward clutch.